The Outcast Devil God of Gremory
by Amaterasu-16
Summary: Keiji Gremory, born as the twin brother or Rias Gremory, not that you could tell from looks though, He was hated from the start for something he had no control over, but is he going to let that stop him from going beyond any limits set before him? Fuck no! follow Keiji as he carves a path through Earth, the Underworld and Heaven alike with his own hands... and maybe magic too.!
1. Chapter 1

**Chapter 1: Cruel Beginnings**

Thousands of years ago, heaven and the underworld were ravaged by what is now known as the 'great war', the angels, fallen angels and devil waged a three-way war that nearly brought the three biblical factions to the brink of collapse. However, after countless years of battle, a ceasefire was proposed between the leaders of the three factions after the loss of the God of the bible and the 4 Great Maou.

With severe losses on all sides, the factions agreed to the proposal and ceased all battles between each other, but this did nothing to resolve the disdain and high tensions between the races thousands of years later.

In terms of losses, all factions suffered greatly and diverted their efforts to rebuilding their numbers, the devils however ended up in a civil war for the power gap that was left following the deaths of the 4 Great Maou, this caused the devils to split onto 2 separate groups, the Old Satan Faction (OSF) and the New Satan Faction (NSF).

After years of fighting, the NSF claimed victory and became the citizens and leadership of the Devils. The devils numbers dwindled to dangerous numbers following the war, which is when it became an expectation for families to produce numerous offspring, especially from between the 33 remaining families of the original 72 Pillar families.

One such house is the house of Gremory. And as of current time, Venelena Gremory, wife of the house of Gremory's current head, Zeoticus Gremory, had just given birth to two children. Usually giving birth to a single child is rare due to the dismal pregnancy rates of devils, so having twins is considered a miracle, but for those present at the birth, there was a different setting.

One of the children, was a crying baby girl, with crimson red hair and blue/green eyes, the second child caused everyone in the room to show expressions of shock. The silent baby boy had silvery/grey hair and eyes of the same colour, everyone present for the birth was shocked, the child held no resemblance to the mother and had none of the Gremory's characteristics such as the crimson hair or eye colours usually seen among blood members of the house.

It was because of these, his treatment and love from his 'family' was decided and he was quickly ignored in favour of his sister the only person who paid any attention to the boy was the head maid Grayfia Lucifuge, she was the 'wife' of the family's oldest son and current Maou, Sirzechs Lucifer.

She walked over to the child, completely unnoticed by everybody present as they doted on the small red-haired girl, and proceeded to lift him from his cradle, smiling down on him softly as the child opened his eyes and gazed up at beautiful figure looking at him with kindness on her usually stoic visage.

The resemblance between the two was uncanny and anyone who saw him would assume he was her own child and not that of the Gremory's. Grayfia was pleasantly surprised to see the child had the same hair and eye colour as she did, it surprised her even more when she felt an immediate connection between herself and the small child.

The child smiled up at her bringing a feeling of something to the normally emotionless woman's heart.

She knew from then that she would have a strong bond with the child in her arms, what she didn't know was just how strong that bond would be in the future. "Grayfia, you should come look at Rias, she is a true Gremory unlike that child in your arms." Spat Zeoticus, visibly angered that the child held no similarity to his honourable and great house, his view shared by the rest of the party that was present except for Grayfia who was smitten with the silver haired child already, and Venelena as she harboured a strong motherly love for her new child, much to the disdain of everyone else.

"Lord Zeoticus, there are already several people attending to Lady Rias, surely your new son should be given the same?" questioned Grayfia coolly, her stoic mask once again returning as she looked at the crowd around the small heiress.

"Does he not also deserve a name?" she pushed, trying to bring sense to those present who clearly disliked the child for no reason other than looking different.

"Bring him here Grayfia." Spoke Venelena softly, her arms waiting to receive her son, a warm smile on her face as she looked at the child in Grayfia's affectionate hold. Grayfia allowed a small smile to flash across her face as she handed the child to the only other person who would love him unconditionally for the years to come.

"what do you think of Keiji, Grayfia?" Venelena asked brightly, ignoring the glares she was receiving from Sirzechs and Zeoticus for asking the maid what name she liked.

Grayfia reached down and gently stroked the smiling child's cheek, "I think it's a wonderful name Lady Venelena." Grayfia replied with a smile as both herself and Venelena looked upon the silver haired child lovingly.

"Come Grayfia, there are matters to attend to." Sirzechs announced, Grayfia nodded in acknowledgement, leaning down she kissed the child on the fore head as he lay in Venelena's, Zeoticus and Sirzechs watched with disgust, both wondering how she could have any affection for the unsightly child.

Sirzechs reached for Grayfia's wrist to pull her away from the child but she swiftly moved her arm from his reach and glared at him, "look after him Ven-chan." Grayfia whispered in Venelena's ear, who nodded in understanding.

They both knew that the child would have a tough life ahead of him and that they would have to prepare him for the world. Grayfia glanced at the child one more time before heading to stand beside Sirzechs who's anger towards the silver haired maid could be felt by anyone in the room.

Sirzechs continued to glare at the maid who simply stood beside him before looking away and transporting both of them from the room via magic circle.

Venelena looked up from her bed to see Zeoticus fawning over Rias and paying not a scrap of attention to his son. She shook her head and looked down at her beautiful son, after a few minutes of simply enjoying the sight of her now sleeping child in her arms she said to him softly, "don't worry my little devil, no matter what happens, you already have 2 people who love you, you little charmer."

"Venelena you should be paying more attention to your child, it is unbecoming of a Mother to ignore their child." Zeoticus declared to Venelena until she snapped her head up to him, her eyes flashing dangerously between her usual purple and crimson, causing Zeoticus' mouth to go dry, "My _child _is in my arms Zeoticus, and don't you think of saying a thing against him or I'll make you regret it."

Zeoticus sneered at his wife before exiting the room as fast as he could with Rias in his arms. Venelena glared at the door for a few more seconds before releasing a sigh, her eyes returning to their usual purple as she averted her gaze to Keiji who brought the smile back to her face as fast as it left, her mind contemplating what she can do for her son to keep his life as happy as possible with Zeoticus and Sirzechs clearly against him.


	2. Chapter 2

**Chapter 2: Clingy Sisters and Lovely Maids?**

Standing outside of a door labelled 'Keiji's Room' was a certain red-head who had a grin on her face as she opened the door and stepped into the room as if she owned it.

Her eyes flickered around the room before settling on the bed where a lump could be seen buried underneath the bed sheets. Rias silently walked towards the bed, stripping herself as she went, her nightgown falling to the floor, followed soon by her panties and bra, for a 12-year-old she was gifted with a beautiful body, already filled out nicely in certain areas.

She reached the end of the bed and crawled onto it, crawling along the bed like an animal stalking up to its prey, she reached her target and expertly manoeuvred herself under the covers, pressing her chest up against the back of the bed's inhabitant.

Her stiff nipples pressed against the back of the lean body in front of her, her hand started reaching down her body inch by inch till she was shocked. Literally. She jumped back off of the bed with a yelp as she fell to the floor bundled in the covers of the bed. She untangled herself from the bed sheets and looked up to see a magic circle crackling with lightning less than an inch from her face, "give me one good reason why I shouldn't shock you till you black out Rias."

Rias looked from the magic circle to the lean, muscled torso and finally to the cold emotionless face glaring down at her. "Mou Keiji, your so mean! We need to practice for when we're married! We need to practice other things too."

Rias stated, a sultry grin on her face as she imagined all the things that could happen between her and the brother she adored and loved when they finally got married.

"first off, that's never happening, secondly, wrong answer." Keiji said without a change in tone whatsoever as he shocked her once more, a slight smile coming to his face as she screamed. He left her lying on the floor as he walked over to his wardrobe, grabbing a pair of black training shorts, a sleeveless black hoodie and a pair of white sneakers to complete his clothing for most of the day since he'd probably be training whenever he didn't have to eat.

He pulled on the clothing he had chose for the day and gave himself a small approving nod as he glanced in the mirror.

For being 12 he had a body that managed to make every woman in the mansion blush when they saw him including the maids and Grayfia, his body had an unnaturally small fat content and visible muscles from head to toe but not to the point he was bulky, but a slim build built for speed and strength.

as he spent almost all-day everyday training in his gym he was physically adept to an unnatural level for his age that in hand-to-hand combat he could fight his 16-year-old cousin Sairaorg to a standstill even though he outweighed Keiji by almost double his weight.

His magic was to an adept level as well, he occasionally sparred against his best friend Riser Phenex and beat him every time they fought in hand-to-hand or magic, even with Riser's Phenex regeneration, when they had first met Keiji had thought that he was the most arrogant ass he'd ever met until he literally beat it out of him, and over time Riser became one of the only people that he trusted.

Even though all of this, Grayfia was the only person who had shown any acknowledgement to his skill and loved him even though they weren't actually related by blood. His mother had loved him at first, but over time she grew distant to the point she was almost like his father Zeoticus and his brother Sirzechs.

He had been depressed for months when his mother had essentially stopped loving him, and the person who had pulled him through it was Grayfia. Grayfia was the only person he could say he loved in the family, but at the same time he loved her in a different way that he hadn't been able to understand for years, his heart would beat faster whenever he was with her, he would actually show any emotion around besides Riser and Sairaorg, but it was different.

He had only been able to understand what it was recently as he had become mature and knowledgeable enough to understand what it was, romantic love.

He loved her in a way that was forbidden as she was married to his brother, even if she wasn't happy about it, plus she was a maid of the Gremory family, and his father the head of the family had banned any relationships between staff and the family. He would admit it to her one day, he just didn't know when that day would be, soon was the closest estimation for how long it would be.

He released a breath he didn't know he had been holding and headed to the door, he grabbed the handle and took one look back at his obsessive sister and smirked at her, she had no visible injuries, but she was lying on the floor unconscious with the occasional twitch or stray crackle of electricity.

He turned the handle and pulled the door open before removing himself from the room and closing the door behind him, leaving her for someone else to take care of.

Keiji immediately turned right and headed down the hallway of the mansion's west wing, taking a beeline straight to his gym, his safe place of sorts, his personal gym was built for him when he was 7 by his mother before she stopped seeing him as a son and started seeing him as a failure.

He made it to the gym door which slid open mechanically, revealing a fully equipped state of the art gym which honestly looked out of place in the mansion, but he wasn't going to complain.

The room was a large 15m by 15m room with a padded spring floor that was firm but provided an almost unnoticeable bounce for shock absorption, there were multiple machines ranging from treadmills to rowing machines to punching bags that recorded the speed, strength and number of his hits in customisable settings.

He kept his stoic façade as he stepped into the room, the door closing behind him as he got to training.

_**-time skip 4 hours-**_

Keiji dropped his hands to his knees, his muscles contracting from the pain they were going through after being pushed to the limit and then past it, breaking them and forcing them to strengthen themselves as they healed.

He breathed in and out at a controlled pace, the pain not showing on his face as he lifted up and stretched his arms above his head in exhaustion, sighing as he felt the satisfying crack of the bones in his back and neck from arching his back as he stretched. He heard a beep signalling that the door was opening as he turned to see who it was, a warm smile appearing on his face as the best person in his life appeared through the door.

Grayfia walked into Keiji's gym and glanced quickly around, before her cheeks lit up red at finding Keiji after his working out. He had long since discarded his hoodie, leaving him in a pair of black shorts and leaving little to the imagination as his body even at his age would probably put most gods to shame, and that wasn't even an exaggeration.

He stood at close to 5'9, slightly shorter than Grayfia's own 5'10, his eyes and hair hadn't changed at all and he could pass for Grayfia's brother easier than he could pass as Rias', his pale skin matched Grayfia's own except for the fact that his was glistening with a light sheen of sweat.

Grayfia blushed even more as her eyes wandered his body taking in every muscle and ab, he had a slim build but that didn't betray his strength at all with him being able to go hand to hand with Sairaorg who is known as the Underworld's 'Strongest Youth'.

"Hey Fia-chan." Grayfia shook her head to prevent any thoughts from entering her mind as she forced her eyes to stop and look at his face, "Keiji-kun, how many times have I told you not to call me that? If your parents heard you'd be in trouble."

Grayfia chided, but secretly she loved it, whenever he called her that she felt her cheeks heat up or her heart skip a beat. Keiji's smile grew even wider as he answered her, "Sorry Fia-chan but until you can find something more fitting for you, I'm going to keep calling you that, at least when we're alone because I don't want you getting in trouble for being familiar with me."

Grayfia felt her heart skip that beat she loved, over the years Grayfia had loved the boy before her, but now that he was maturing, she felt that love becoming something else, something she had never felt with anybody in all her years alive.

She knew it was wrong but to her it seemed right, she wished that there was a way for her to be able to be with him, but as long as she was stuck with Sirzechs as his wife and queen of his peerage, there was nothing she could do.

She didn't love Sirzechs. Never had and never will. In the Devil Civil War, he killed her towards the end of the war and reincarnated her as his queen and told her that if she didn't accept being his queen and getting married to him then he would kill her once again.

Grayfia had accepted as she had held onto the small hope that someone would be able to save her from him. She had even managed to keep her chastity, and in her mind she hoped to give it to a certain someone who she had even fantasised about a few times during her time alone, she even lived alone in a beautiful small two-floored mansion instead of living or sleeping with Sirzechs.

He'd tried to get her to sleep with him many times but had been turned down countless times and during the times he tried to force her she threatened suicide or running away.

Grayfia brought herself back to current time and covered her mouth with a hand to hide her smile at his answer before replying, "very well, as long as its when we're alone." Grayfia lowered a hand and lost her emotionless mask completely as she made her way over to the young man with a caring smile and cast a quick spell to get rid of the sweat and cool him down.

"Keiji-kun, Zeoticus has asked that you be present for lunch with your family as your brother will be home." Grayfia told him, a slight amount of venom in her voice at the mention of Zeoticus and Sirzechs, Keiji being the person closest to her picked up on it instantly, and asked, "you don't love Sirzechs do you Grayfia?"

His voice lost its playfulness and took a slightly more serious yet caring tone as he asked her. Her eyes widened slightly before her head dipped and sad look adorned her face.

"that's right Keiji, you're the only person apart from Sirzechs himself who actually knows that though." Keiji felt something at her words, hell, he felt multiple things at her words. Hope. Anger. Pity. Love. And that's only what he could feel easily.

"One day Grayfia, I'll save you from him, I promise." Grayfia raised her head, her eyes tearing up at the sincerity in his voice, someone actually caring about her and promising to save her.

A single tear escaped her as she moved forward, her head resting on his shoulder as she collapsed into his embrace, holding on as if he were her last life line, her arms wrapped tightly around his shoulders, crying quietly as he held her, letting her get out the feelings she always has to bottle up with anybody else. "please... one day... please save me Keiji-kun."

Grayfia managed between silent sobs, Keiji responded by gently pulling her away so he can look at her face as she responded, "I promise Grayfia, I promise. I'll get strong, defeat that bastard and set you free."

Grayfia looked into his eyes and blushed at seeing the fire in his eyes as he spoke with fierce determination. Grayfia smiled and closed her eyes as she pulled Keiji into another hug, pressing him against herself, "Thank you Keiji." She whispered softly, her heart beating fast in her chest as she felt the spark of hope inside of her grow ever so slightly.

Grayfia pulled out of the hug, straightening out her maids' outfit as she clicked her fingers, magic cleaning up her appearance so she looked presentable before the terrible people she was serving under. Keiji quickly moved and grabbed his hoodie pulling it on after Grayfia used another small bit of magic to have him smelling pleasant compared to the sweaty smell from before. "Come on Keiji-kun, the others are waiting for you."

Keiji gave an audible sigh before giving Grayfia an understanding smile that brought one to her own face as she left the gym, schooling her features as she continued onwards down the corridor to resume her duties as head maid. Keiji exited the gym shortly after and headed down the same way but turning at a different point, opening a door and entering into the dining area.

"Keiji where have you been? And where is your sister?"

Asked Zeoticus, a fake smile on his face as he addressed his youngest son, Keiji looked towards him with his usual emotionless expression that mirrored Grayfia's own before answering, "I've been working out in my gym, and Rias is probably still passed out on my floor."

As the words left his mouth Zeoticus and Sirzechs' auras flared to life, their plastic smiles gone and replaced with anger, "what have you done to her Keiji!?" shouted Sirzechs, his sis-con nature kicking into overdrive as he glared daggers at Keiji who didn't even flinch.

"I shocked her till she blacked out." He replied simply, "and why would you do such a thing?" Zeoticus growled from his seat. "because that brother-complex of hers is annoying the shit out of me, she keeps trying to fucking sleep with me naked as the day she was born and is clearly bat shit crazy if she ever thinks I'll reciprocate those fucked up feelings."

He answered smoothly, his voice and features not betraying a hint of emotion as he said it all, moving towards his seat and sitting down to start on his food.

At that moment the doors burst open and a cheerful looking Rias skipped into the hall without a care in the world which honestly wasn't far from the truth. Zeoticus and Sirzechs were immediately across the room their auras gone as they fussed over Rias to make sure the stuck-up little princess was fine.

Rias eyes settled on Keiji after assuring her loving brother and father that she was absolutely fine and proceeded to walk over to him, her hips swaying as she walked towards him.

Her face quickly turned into a pout as she saw him not paying any attention to her whatsoever, she stomped over to him and slung her arms over his shoulders from behind talking into his ear, "Keiji-kun, how about after dinner we go and do something fun? I'm sure a big. Strong. Boy. Like your self knows what I mean and would love to do it with me."

Her voice taking a seductive tone that didn't faze him in anyway as only one person could ever get his love and it certainly wasn't his crimson haired brat of a sister. Keiji channelled a small amount of ice magic through his body, dropping his temperature to a freezing point causing Rias to squeal in shock and remove her hands from him whilst he stayed relatively warm in comparison, completely unaffected by the magic.

"I'm leaving, thanks for the meal." He spoke monotonously as he stood and headed to the door, Rias tried to pursue him but found herself stuck to the floor due to the ice keeping her feet locked in place.

"Mou, stop playing hard to get Keiji-kun and admit your feelings for me!" Rias yelled as she tried to no avail to get the ice off of herself.

Sirzechs of course was helping her almost immediately and was grudgingly impressed that the ice magic actually took some effort on his part to remove.

Keiji closed the already opened door behind himself and headed to his room to quickly grab a towel and some compact weights from his nightstand that he wears in his wrists and ankles, they progressively increase in weight as he acclimates to the current weight.

He also grabbed a bottle of water from his fridge and made his way back to the gym to train for the remainder of the day in both his physical and magical areas.

'_one day Grayfia, I'll be strong enough to save you, until then ill train and become strong, no matter what I have to face' _Keiji thought, a goal set in his heart, his determination burning hot enough to destroy anything in the way of his goal.


End file.
